Person localization and identification are indispensable to provide various personalized services in an intelligent environment. We propose a novel method for person localization and developed a system for identifying up to ten persons in an office room to realize soft authentication. Our system consists of forty-three infrared ceiling sensors with low cost and easy installation. In experiments, the average distance error of person localization was 31.6cm that is an acceptable error for sensors with 1.5m distance to each other. We also confirmed that walking path and speed gives sufficient information for authenticating the user. Through the experiments, we obtained the correct recognition rates of 98%, 95% and 86% for any pair, any three people and all ten people to identify individuals.